The military will begin enforcing President Trump’s restrictions on transgender troops on April 12, according to a Pentagon memo, which drew rebukes from Democratic lawmakers and civil rights advocates who decried the change as bigoted.

The memo stipulates that a history of gender dysphoria would disqualify applicants to the military unless they have been stable in their biological sex for 36 months, are willing to abide by the rules for that sex, and have not transitioned and do not need to in the view of medical providers.

Those who are already in the military or under contract to join before the start date will fall under the 2016 policy enacted by the Obama administration. That policy allowed people who have transitioned to join the military and gave those already serving an opportunity to transition while in the armed forces.

It also allowed service members to change their gender marker in the military system and abide by uniform, grooming and facilities rules for their new identity.

None of that is allowed under the new restrictions.

Under the new policy, secretaries of the military services will be given latitude to grant exceptions to certain individuals, who would then be able to access medical care in accordance with the old policy.

The decision by the Defense Department to begin enforcing the policy comes more than a year and a half after Trump announced the ban by tweet in July 2017, surprising his own defense secretary.

“After consultations with my Generals and military experts, please be advised that the United States Government will not accept or allow Transgender individuals to serve in any capacity in the U.S. Military,” Trump wrote at the time. “Our military must be focused on decisive and overwhelming victory and cannot be burdened with the tremendous medical costs and disruption that transgender in the military would entail. Thank you.”

The actual Pentagon policy that former defense secretary Jim Mattis formulated and rolled out after the tweet stopped short of a categorical ban, according to defense officials. It allows transgender individuals to serve in the military, as long as they aren’t diagnosed with gender dysphoria, haven’t transitioned sex and don’t need to, and submit to rules for their biological gender regarding uniforms, grooming and facilities.

Critics, however, say those rules amount to a de facto ban, because they essentially allow transgender people to serve in the military only if they refrain from transitioning or engaging in activities that allow them to live out their identity on the job. The policy also bans those who have already transitioned sex from joining outright.

Democrats, who are hoping to reverse the ban through bipartisan legislation, criticized the Pentagon’s decision to begin enforcing the measure.

“Anyone who is qualified and willing should be allowed to serve their country openly,” House Armed Services Committee Chairman Adam Smith (D-Wash.) said in a statement. “Make no mistake, this is a discriminatory ban on transgender people, not a ban on a medical condition, and we will continue to fight against this bigoted policy.”

Civil rights advocates said transgender individuals should be able to serve in the military like everyone else who meets the standards required for the job.

Jennifer Levi, transgender rights project director at GLBTQ Legal Advocates and Defenders, called the Pentagon’s enforcement of the new rules “deeply immoral and deeply insulting to the many transgender troops who are bravely serving their country.”

“Military leaders, medical experts, and the vast majority of the American public agree that our troops deserve gratitude and support, not a slap in the face based on bias and irrational fears,” Levi said.

Defense officials say they have no way of tracking the number of transgender forces in the military, but according to self-identification, they believe 9,000 individuals identify as transgender, about 1,000 of whom have been diagnosed with gender dysphoria.

The rollout of the memo days before acting defense secretary Patrick Shanahan is due to appear before the Senate Armed Services Committee on Thursday adds a level of tension to a testimony already expected to include hostile questions over Trump’s decision to take Pentagon funds without congressional approval for a border wall.

Shanahan, a former Boeing executive who is hoping to get the nod from Trump to replace Mattis, has testified before Congress only once before, during his confirmation hearing to become deputy secretary.

The Pentagon’s decision to press forward with implementing the new restrictions comes after several court cases challenged the measure, leading to injunctions that delayed implementation for months.

But in January, the Supreme Court, in a 5-4 vote along partisan lines, allowed Trump’s broad restrictions to go into effect. The legal battle continued in the lower courts, and lawyers representing the claimants have argued that ongoing proceedings in the U.S. Court of Appeals for the D.C. Circuit should have prevented the Pentagon from moving ahead.

Attorneys for transgender service members in the federal case in Washington said in a filing Wednesday that the government’s “official order directing a change in the government’s policy regarding transgender service members violates the injunction in this case.”

“The government may not depart from the status quo or order any new policy inconsistent with that injunction,” the lawyers said, until they have had time to decide whether to ask the full D.C. Circuit to review the ruling of a three-judge panel.

“Defendants are disregarding both those interests and the authority of this Court. They must not be permitted to cast aside the ordinary procedures that safeguard those constitutional interests, nor may they be permitted to usurp the Court’s jurisdiction to determine when its injunction has expired,” according to the court filing.

Because the Pentagon restrictions do not go into effect until April 12, the court proceedings theoretically could be resolved by then, though it would be a quick turnaround. If they progress past that date, the Pentagon could be forced to further delay implementation.

Transgender-rights activists, meanwhile, have been urging the public to get behind the legislation proposed in Congress in a bid to override Trump’s decision.

“We will continue our fight in the courts until the ban is permanently blocked,” said Shannon Minter, legal director of the National Center for Lesbian Rights. “We also strongly support the bipartisan efforts of congressional leaders to pass urgently needed legislation to protect transgender troops. We urge everyone who cares about the integrity of our military and the well-being of our troops to contact your representatives and tell them to support this legislation.”